The present invention relates to an image recording method and apparatus for describing a virtual space on the basis of sensed images and, more particularly, to a method and apparatus for processing sensed images from a plurality of cameras which are separated from each other as if they were obtained from cameras which are not separated from each other. The present invention also relates to a recording medium that stores a program for implementing the method.
In recent years, attempts have been made to build civic environments where many people socially live in cyber spaces formed by computer networks. Normally such virtual spaces are described and displayed using conventional CG techniques. However, since CG expressions based on geographic models have limitations, Image-Based Rendering (IBR) based on sensed images has come to the forefront of the technology.
Reproducing sensed image data as they are amounts to merely experiencing what a photographer has gone through. For this reason, a technique for generating and presenting an arbitrary scene in real time using the IBR technique has been proposed. More specifically, when sensed images are processed as independent ones, and are re-arranged in accordance with a viewer's request, the viewer can walk through his or her desired moving route at a remote place, and can feel a three-dimensional virtual space there.
It is effective for searching for and re-constructing a desired image in accordance with the viewer's request to use the location information of points where the individual images were taken. That is, an image closest to the viewer's request is selected from a database, and undergoes proper image interpolation so as to generate and display an optimal image.
FIG. 1 shows the principle of wide-area walkthrough using sensed images.
More specifically, sensed images are prepared for narrow areas 1, 2, 3, and 4. In order to implement wide-area walkthrough (e.g., along a route 10 or 11) that allows the viewer to walk across these narrow areas, an image in a space between adjacent narrow areas must be obtained by interpolation. When the viewer is currently located at a position between the narrow areas 2 and 3, and the space between these areas is obtained by interpolation, specific sensed images for the areas 2 and 3 must be obtained by a search on the basis of information associated with the current location of the viewer between the areas 2 and 3. In other words, in order to obtain required images by a search on the basis of the location information of the user, a database of sensed images must be prepared in advance in accordance with location data upon image sensing.
In order to attain precise interpolation and to smoothly connect the interpolated images and sensed images, as the viewer may walk through in the 360° range around him or her, sensed images of the environment must be taken by a large number of cameras disposed to point in various directions, and an image database must be built using these sensed images.
In order to attain precise interpolation on the basis of images obtained using a plurality of cameras, the image sensing centers of many cameras must agree with each other. However, it is not easy to arrange many cameras in such way.
To solve this problem, conventionally, a plurality of mirrors are set symmetrically about a given point, and the mirror surfaces of the individual mirrors are set so that light beams coming from the surrounding portions are reflected upward, thereby setting the image sensing centers of the cameras at one point, as shown in FIG. 2.
However, in the mirror layout shown in FIG. 2 it is difficult to prevent the photographer (vehicle) from being reflected in the mirrors.